This invention relates to the control of oversprays from paint spray booths and more particularly to deflocculating compositions useful in the recirculated water systems utilized in the washing of oversprays of paint and other coatings from air.
To contain the overspray from paint spray booths, the painting area is typically surrounded by water curtains created by overhead nozzles. For economic reasons, the water is recirculated until it is saturated with paint wastes. The use of pure water is unsatisfactory because of its limited capacity for maintaining paint wastes in dissolved or suspended states. The wastes therefore rapidly saturate the water and then separate therefrom as a very troublesome sludge. Furthermore, chemical and physical interactions between the paint constituents and the water create voluminous foams which reduce the efficiency of the water curtains and often cause the recirculation system to overflow.
To increase the paint-holding capacity of curtain waters, sodium hydroxide is typically added as an aid in decomposing the resin systems typically used as vehicles for the paint pigments. The beneficial effects of using caustic alone are minimal and the formation of sludge and foam are generally not avoided.
It is also known to use combinations of ingredients for enhancing the paint-holding capacity of curtain waters. One such combination of ingredients includes sodium gluconate, sodium bitantrate, triethanolamine, sodium hydroxide and a wetting agent.
It is an object of this invention to provide deflocculant compositions which, when added to air-wash systems, will effect digestion, dissolution and/or suspension of paints and other coatings to a degree not heretofore obtainable. It is a further object to provide deflocculant compositions of the type described which, when added to such systems, will prevent or reduce the formation of foams, inhibit the corrosion of steel, reduce the toxicity of paint-saturated waters and reduce or prevent the growth of slime-producing micro-organisms.